Providing a challenge

[Yoven]

Hello guys,
i am going to throw the Party that is playing with me into a Bossfight soon and need some advice.
The Group is of only 3 Players all on lvl 6 with average optimization. (No really stupid choices of Attributes or Feats, but its a core only game) They're consisting of a Sorcerer who mainly throws Fireballs at any target that gets in his way and also has a good chance of hitting some of his allies with it, a Ranger with ranged build and a Cleric.

The setting is a Town haunted by undead due to some sort of curse and the source to this curse is a Book inhabited by an evil soul. Now when they stab the book i need a challenging but not PK bossfight coming up.

My Idea so far was to let the soul shape into the form of a morgh (CR8), and maybe give him one level of cleric to cast one instance of protect from good and doom. The Morgh has a chance of 45% to hit the Cleric (Tank of the group) and will pretty sure always hit the Sorcerer and Ranger. They have no Potions or else against the paralysis of the morgh because they ignored the ones i placed in the game. I think of adding a few zombies to the fight because i think single target boss fights tend to be over pretty fast and some sort of distraction is always nice.

Now i just want to know how high the chances are they're going to die and/or if there are none except for the chance the sorcerer fireballs them all on 1/2 Hitpoints, how to make that fight a little more challenging.
You can assume that they enter the fight with Bulls Strenght, Divine Favour and bears endurance

[Cespenar]

There's a good chance that the mohrg by itself could manage a TPK pretty easily, due to the group's optimization level and number of players. I mean, stuff like friendly firing with fireballs? That happens in probably in the early stages of first or second edition, and perhaps a D&D-themed webcomic or two, never mind an optimized party.

If you really want, you could add a couple of zombies to equalize the numbers, but my money would be that the mohrg alone has a good chance to TPK the group. I mean, it all comes down to a first round paralysis.

[Yoven]

i hope at least the cleric and probably the ranger will be able to shake off paralysis, maybe i'll "guide" them to two potions of cure paralysis...

frindly fireballing came from the idea to shoot afireball through a 5inch hole in a door 15feet away. He failed the touch attack to do so so it hit the door and blew them up.

[Novawurmson]

I would say give it some skeleton/zombie trash (the PF skeleton archer might be good (http://www.d20pfsrd.com/bestiary/monster-listings/undead/skeleton-medium/skeletal-medium-archer)), but then purposefully use its slam attack for 1-2 rounds before paralyzing anyone.

(Also, random: Shouldn't it's flat-footed AC be 19? The SRD lists it as 14 (http://www.d20srd.org/srd/monsters/mohrg.htm)).

[Yoven]

seems to be an error you're right. Its also wrong in my version of the MM

[GenghisDon]

a Morgh should be fine. It's always hard to say, not truly knowing the characters, but even adding a few zombies shouldn't matter, at all. They will be turned or fireballed in round one.

I'd give them some warm up zombies (say 12) to boot, an easy encounter for them, despite a high EL.

The ranger might struggle a bit, unless he's anti undead in some way, but don't make the next adventure about undead if so.

Adding the cleric level might really increase it, not via L1 spells, but by scores inflating, gear, and an extra feat. Undead HD are already inflated in an attempt to counter design flaws, adding more becomes dangerous.

[Yoven]

okay i'll pass on the evil cleric level then.
They don't need any warm up as they are already smashing zombie-heads and ghouls and boneclaws and stuff for some time now...
Fireballing will be hard as they have to stand close to the book and stab it to make the morgh appear... and i'm quite sure that the sorcerer won't get stand far away when they do that. And even if he does, friendly fireing the cleric and/or ranger when fighting a serious threat would be really stupid.

[Alefiend]

Is stabbing the book really necessary? I would douse the thing in oil and set fire to it—that might circumvent your whole encounter, or at least start it in a way that give the party an advantage. Burning morghs are not happy morghs. Be conscious that your players might come up with a clever idea that makes your plan pointless.

If you're dead set on having somebody stick a knife into this book, maybe it has to be a special blade, which will also be extra-useful against this opponent. Immunity to paralysis, undead bane, something like that.

[Yoven]

well they can set it on fire if the want... also from range, but i'm pretty sure they won't do it.
Also i wanted the book if beeng destroyed in the right manner (some sort of ritual they kno about) to turn dark and burn, then create some magical darkness, growing the morgh out of his soul and the book, levitating, then landing on the ashes of the book...

so the morgh may burn, but only after beeing shot with burning arrows or fireballs or scorching rays.
There's no special weapon against it and it is now to late to place one as the are about 10 minutes away from the encounter.